The Window Wedgie Widget

 A couple of weeks ago, we were camping our way across the West on our first long trip - the two of us

and our two fur kids in the teardrop for two weeks from Minneapolis to Oakland and back.  And on the second night out in Veedauwoo Wyoming, it was downright chilly!  To keep from totally steaming up the trailer, a little ventilation is essential (and my safety vent isn't enough).  So I latched the window open and dealt with an icy breeze blowing in on my delicate backside.  I did figure out that you could sort of 'jam' the window partway open, but still...

So sitting at my computer a few days back, I thought about those nights and decided there was a better way - enter the Window Wedgie Widget (or SW-W3 for short).  And pretty soon every problem starts to look like a nail if you have a 3D printer.  So I whipped out a few prototypes that evolved into this - the Window Wedgie Widget.  The left hand picture is deployed in the 1.5" position.  Flip it vertical and it gives you 3.5" of gap.  It's made of plastic, fits snugly in the track, and stows - well wherever you want to stow it!

This works great.  I did a solo weekend trip to Arkansas, left this in every night, and had zero condensation - and no frozen backside (ok, it wasn't really that cold - the heater only kicked on once the whole trip).  

If you are interested, please drop me a note and I'll be happy to send you one or a pair of your very own.  I am selling these locally and on ebay at $9.99 for one, and $15.99 for a pair (plus shipping). Right now, I'm only making in Henry Ford's favorite color - black - but colors are a possibility too.

I'm also making a variety of other widgets to fix common problems - spacers, hole covers, anti-rattle shims, tube ends and so forth.  If you need anything like this, please drop me a note.  If I don't already have something, chances are we can figure something out!

Galley - a work in progress

 The galley end of the trailer is very definitely still a work in progress.  There are a number of tasks still to be completed before it's really functional, but you can get an idea of the basic shape.

The 45 liter Iceco was a great addition.  One of the keys for me is that it runs on 24 volts, which means it doesn't need the voltage stepped down (or worse- run thru the inverter).   You can also see the Propex heater installed on the lower left wall.  Like the stove above it, it's awaiting hookup - I need the bottle mount to arrive so I can mount it and the regulator outside, and then will plumb it to the two units.  Eventually, there will be a water jug in the propane bay, and some drawers in the leftover space between the two sides.

Both the fridge and Camp Chef stove sit in finger-jointed box frames made from 1/2¨ Baltic birch, and cut on the CNC.  I learned making the first one (which fit the Iceco too tightly) that when CNC'ing interlocking fingers, you do need to leave a little clearance between them.  So making the pins .98¨ and the gaps 1.02¨ worked out just right.  They're glued up with Titebond II, and finished with a few coats of Total Boat water based varnish.  I cannot say enough good things about Total Boat products.  They are not cheap, but you definitely get your money's worth.  Easy to work with, dries quick, and great support.  I've finished a boat, and this camper with their product, and I absolutely love it.  And no, they don't comp me.

The back wall is still a work 'in study'.  I decided that the right half would be used for electricity related 'stuff', like switches, fuses, meters, etc, and the left side will eventually turn into storage for kitchen gear.  I'll put some sort of doors over the electrical bay so that it doesn't spoil the view.

An earlier shot of the right hand bay.  I'll pull the fridge and get a 'final' shot, but at the moment - here it is.  
Widget ID starting from the top right -
Epever 20A MPPT charger.  I tried to balance cost/performance.  This can handle the current 200 watts of solar, plus another set if I were to choose to add them later.  
Victron IP67 5A charger - will be connected to the shore power side of the transfer switch.

Fuses and wiring
12v buck supply - to step down 24v to 12vdc for lights,  the heater, fan, etc.  40A should power everything with more than a little room to spare.

Here's the Propex all vented in, and the 2500W inverter.  I got the inverter when I was planning around a 5000BTU room air conditioner, and needed AC power.  Now that I have an AC unit that will run on 24vdc, this is gross overkill, and I'll probably sell it and replace with something about half the size.  The biggest thing I anticipate needing AC for is a small Instapot.  It draws more power than the fridge does when in idle state.  

What isn't shown here is the battery pack - 16 50Ah LiFePo4 cells wired series parallel to provide 24 volts 100Ah of usable power.  I'll add that to the walkaround.

 That about wraps up the galley at the moment.  As you can see in a couple of pics, this is a work in progress.  I still don't know what all the nooks and crannies will be used for, but we'll figure it out as we go.  

Soft launch!!!

 

It's done - or at least somewhat usable...  It's been almost exactly one year since my wife and I first talked about the idea of a teardrop (since the motorhome was a non-starter).  I spent a month or so researching, watching youtube videos of manufactured trailers, people's video blogs, youtube channels, personal blogs, and Tony's book, ¨Building a Teardrop Trailer¨.  And by October, I'd decided that I could build what I wanted, instead of buying it.  There are a lot of cool trailers out there on the market, and I didn't build because they weren't available, but rather because they didn't tick all the boxes - or mostly, ticked too many!

When it was all said and done, I wanted:

• A queen sized bed
• Simple storage
• Heat
• AC
• Fan
• Stove
• Fridge
• No plumbing

What you see here is the 'soft launch' - mostly done, but still a lot of cosmetic touches to finish up, a lot of seam sealing, and a few things left like hooking up the AC, hooking up the propane system for heat and stove, and some more cosmetic touches.  

The really important stuff - it tows well, the mattress is comfortable, it breathes, and I think it shined up pretty well.  I have to admit I took a step back when I pulled off all the blue and really got to look at it.  

I'll do a couple of additional posts over the next few weeks, including the always questionable 'cost sheet'. 

A bunch of little (and not so little) things

 It's been a couple of weeks since I did a 'real' update.  It's not that I haven't been working on the trailer, but rather because most of it hasn't been blog/photo worthy.  Except that I forget that some of the things are big milestone items.  Over the past 3 weeks, I've been struggling with 'the hatch'.  It has been bit my own nightmare in the making, so when I realized that the hatch I built just was not going to work, I have consigned it to fuel for the Solo stove and started over.  The new design is much more along the lines of the 'standard' with heavier multi-component side rails and lateral stringers.  I should have a post on it next week.  I'm also making headway on getting the battery pack assembled and wired, and on getting the shore power/transfer switch installed and wired.  

So to keep things moving and allow me time to think about hatch mechanics, I have now:

• Installed the doors
  
  There are _tons_ of good videos on door installation.  I've gone thru a couple of rolls of butyl tape getting them in place.  Sticky stuff!  For reference, I went with the Challenger doors.  Less expensive, and OK for quality, but I don't have a good frame of comparison.  They were being purchased by Lippert at the time I ordered the doors, and delivery was 10 weeks.

• Installed the MaxxFan
  
  I made a (correctable) mistake doing the final cut on the roof. Fortunately, it was cosmetic only and never to be seen by anyone.  For guidance, when cutting the top, it's adviseable to drill all 4 corners, and then draw lines between the holes - and maybe even paint tape to protect the paint from the saw.  It's easy to get an aluminm chip between the skin and the base of the saw.  Once you get the rough cut with a jigsaw, it's easy to make one final pass with the trim router and a flush cut bit to trim the hole back to the 14" frame dimensions.  Butyl tape to seal the fan into place and carefully tighten down the screws.

• 
  Installed the Propex heater (well physically anyway)
  This is an(other) install that has morphed a bit as physical reality met initial visualization!  I cannot overstate the complexity added by air ducts...  They do not simply mold into space- you have to account for bends, interference and inflexibility.  As you can see from the picture, I have an interference between the corner of the inverter and the hot air duct. That would last perhaps one trip before it rubs thru.  I'll print a cradle  for the duct that should protect it from abrasion.  I also raised, and offset the heater by an inch or two from the original mounting to give a little better bend radius for the ducts.  This isn't a big deal, and where the lines pass thru the floor will get centered/sealed as well.  

• Designed/printed registers for the AC ducts
  This was a relatively simple task.  Visualizing designs in CAD has become a lot simpler for me, and it's cut trial and error down to a couple of iterations.  In this case, I initially tried to make the blades too fancy, which resulted in a less than stellar print.  Second  try I also angled the blades to give a little direction to the airflow.  It's a little time consuming, but with a decent printer, not too challenging.

• Tossed out the plan to use a big ugly black metal box for the tongue box and gone with a svelte hand designed and cut one, mostly using scraps.  And it's looking good (so far)
  The profile of the box parallels the front of the trailer, and mimics the curve.  I'd convinced myself it would be too much work, but in hindsight - I'm an idiot:)  
  The hatches came in last night, and I'll cut the end caps to mount the hatches.  
  
  
  
  
  
  
• One [more] thing I didn't account for very well - the ductwork takes up a *lot* of space!  It'll all work, but I think the kibble bag may wind up staying in the car!  The box is big enough to add a few tools, but the ductwork does limit some utility.  It looks a lot sharper than the big metal box!  

Printed material

One of the most frustrating parts of a build are the little odds and ends that are required - adapters, plugs, grommets, vents, and other weird little widgets made of plastic and filling those 'specific purpose' needs.  The pursui t of which involves finding that none of the local suppliers have anything close, searching the net, finding something sort-of close, ordering it, waiting days for it to arrive, during which time your project is on hold, and then finally getting it and learning it... doesn't fit.  

I'm fortunate to have both the 3D printers, and some reasonable beginner CAD design skills to be able to visualize many of these, design a prototype, and then print it.  Sometimes it works, sometimes it takes a couple of attempts to get it right.  But with an hour of my time, and a couple of hours to print it, and I can quickly validate my assumptions, the part fit, tweak it a bit if needed, and it's ready to use.  

One example of this is the new ZeroBreeze Mk II air conditioner.  The Zero Breeze box contains the necessary ducts and fittings for the AC end, but nothing for the end of the duct.  Since my AC will be mounted in the tongue box, and piped back into the trailer body, I really didn't want the outlet to be a 4'' diameter piece of white plastic tube poking into the trailer!  It took me about 30 minutes to draw out in FreeCAD, 8 hours to print the prototype, 10 minutes to make changes to the louvers and outer chamfer, tweak the thickness, and then a second iteration to print (5 hours) a production quality version.  One feature of this version is that the louvers are angled 10 degrees to aim the air away from our heads while sleeping. 

There are a bunch of items that I've done the same for - from a pad for the bottle jack to fit over the 2¨frame tubes, to end caps for the rails, to collars for cable routing, and wire-way covers for burying wire in the walls.  I've included most of them in 3D prints for Teardrop build.  Feel free to copy, or if you see something you need, I will be happy to sell them as well.  I'm also available for design/prototype and custom print work.

I need to print two more - one for the return air, and a hot exhaust for the bottom of the box.  The one going out the bottom will have a little longer snout, and will have a 'lid' to clamp in a piece of screen to keep critters and insects out.

Agile Development

Especially for those in the IT world, the term ¨Agile¨ is usually met with both joy and trepidation.  Done well, it's one of the best things that has every happened to project management, software development, and well, almost anything.  However, it's rarely done 'well', and we'll leave it at that since this is a family show.

This project is possibly the most agile project I've ever done.  Everything about it has been an iterative design.  Almost nothing is exactly as I originally sketched it out, and design goals have shifted as I learned new things.  There are also things like the A/C system I mentioned in an earlier post that drove a major change in the front end, and the ripple from *that* change has kept on giving all the way to the back of the trailer.  In some ways I wish I'd waited to order the inverter - I originally bought with the expectation that I could run the house AC unit on battery for a couple of hours a night and recharge either via solar or plug-in.  Since the new AC runs on 24vdc, I now have a 2500 watt inverter to run the Instant Pot, and to charge laptops.  Just a little overkill, I think.  But it's bought, paid for and too long out of the box to return, so I'll bolt it in anyway.

The board above will get screwed in to the back of the bay.  The batteries will mount on the floor, taking most of the clear space at the bottom.  What's not shown here (future post) is circuit protection, AC switching, the master switch, etc.  That's all going up above the counter where they can be accessed without performing contortionist routines.  And I still have to balance and assemble the battery pack and BMS - not hard, but somewhat tedious and it does require a certain amount of care to avoid arc welding with your fingers.  At the end of the day, I'll have 100aH 24volts of LiFePo4 battery stuffed behind the wall to power all the creature comforts.

 

It's really blue right now...

 

I feel like I need a little Christmas tree to put on top!

Tonight was a big step - the last major bit of aluminum (but not the last major bit of work) is on the trailer.  

I called it a wrap tonight with the panel on and secured with screws and clamps. Tomorrow I'll start over at the back, unclamp it, contact cement a section, get it glued down, and then do the other half/thirds.

The top panel is 5x10x.100, which is a bit heavier, but means there are no seams on the top from the hurricane hinge forward to the 'tongue box' - or what I'd planned to be the tongue box.  

To say there have been a few design changes along the way is being kind.  As mentioned in the last post, I had initially planned for a window air unit in the tongue/utility box.  Moving to a commercial box means I have a lot less complexity up front, but does mean I have a front panel to close up. 

Once the side panels were glued down, I used a jigsaw to get close - typ 1/4¨ and a trim router with a cheap import carbide bit to bring the panels down to the correct line.  One tip on the jigsaw - make sure you get the right blade - the very thin metal blade clogged up so quickly that it was unusable after only a foot of .040.  The 'thin' blade worked fine.  Vacuuming up all the bits of aluminum was a major effort!  And even though you see all the junk piled inside, I did protect the inside to keep the chips out when cutting the sides.

Next up - the front panel and the hatch.  Any bets which one is going to be more work??

Diamonds

 

Today was the start of one of the last major steps in the build - skinning the outside!

I chose to add diamond plate to the lower sides, and to the nose, wrapping back about 9 inches around the front.  I actually did this for a couple of reasons.  First, the diamond plate provides an exta layer of protection for the parts most likely to get rock chipped or dinged from things I can't control.  Second (and probably more important) I could not get a 5x12 sheet of .040 aluminum at anywhere close to a reasonable price or distance.  Since the trailer is about 123 inches long and 56 inches high, this allowed me to skin the trailer without any awkward seams.
If the weather cooperates, the outside could be all skinned up by Tuesday!

On other subjects, I've finally made a number of decsions about things like AC, heater position, and tongue box.  For anyone in IT or project management - this is hands down the most Agile project I've ever done.  The entire design process has been very iterative, making significant changes based on the learnings from the previous sprint.  It's almost literally run on two week sprints, I've had to assign 'story points' to tasks, the definition of 'done' keeps shifting based on progress from each sprint, and so on.  

One of the areas where this has been most apparent is air conditioning.  i thought I had this wired. I had been planning all along to use a small 5000 BTU window AC, sized the inverter to drive it easily, and laid out the headboard to accommodate it.  But I was struggling with mounting the thing in the tongue box, whether I should get a commercial one and surgically alter it, or build one.  At the same time, I kept seeing ads and videos about Zero Breeze.  So I started researching it, and liked what I read.  And it runs on 24 volts, so that really means the insta-pot is the only major use for the inverter!  NOW I have to string new wire from back to front.  I'm glad I buried a pull string in the wire-way.  I'll pull a new one along with the 10Gauge wire just in case there's something else that needs to go in.  

Roof, roof! (and other bits of progress)

 OK, it _still_ a really bad dad joke, but that's where we are. The roof is more or less installed.  There are
some spots that I need to go back and countersink screws - edge grain of plywood has slightly better zero holding power, especially for staples.  And there were a couple of interesting 'learnings' - like the fact that the point at which a 5 foot sheet lands on the inside of a frame is very different from where it lands on the outside - didn't take that into account...

The last was fairly easy to address - the end of the panel was in a relatively flat spot and right in the middle between frames, so I added a 1/2 inch doubler and screwed both sheets into that - worked just fine.  I also used Weldwood III instead of my normal II in order to gain a little more work time - we've gone from too cold to nearly too warm in the matter of a week.  

The other project of the week has been the hatch.  I'm still not convinced it's right, but I'm going to run with it for the moment.  There are a few 'fit and finish items that I think might be improved upon.  BTW, you can see the green 'lunch counter' through the hatch.

The hatch is seven 3/4'' ACX ply ribs with basswood stringers, a 4¨ oak top plate, and a 3/4¨ oak sill plate. The former will provide strength for the hinge, and the sill plate should be strong enough to latch through.  

The sides will go on this week, weather permitting.  My plan is to position the side, add a few screws for a 'ledge, and then roll on a good coat of contact cement - press it on and pressure roll it into place.  

Baahh, baahh!!!

 Big week on the build.  As of tonight, blocking between spars is complete, insulation is installed on the ceiling, the roof has been kerfed, wiring has been run for lights, the fan, switches, interior lighting has been installed, and I've finally got a decent layout for the electrical system!

After a lot of thought, a bit of research, and a strong desire not to cut and kerf a bunch of pink foam, I decided to go with Havelock wool insulation.  Havelock sells a box of 100 sq ft for $150 plus shipping, which when you add up the cost of foam board (~$100), the amount of time spent cutting and kerfing the foam, I'll do without the extra 2 points of R value on the foam, and not buy a couple of beers to pay for the difference.  

This went in easy - the wool is in 4 ft x 16 in x 2 in batts, and it's simple to cut with a good pair of scissors.  Since my spars are spaced 8¨ apart for the most part, and the stringers are roughly 24 inches from the side, this was a pretty quick task.

Blocking is screwed in - pocket screws up front ensure I could screw the AC duct in line with it, and mostly end screwed through the spars on the back side.  Either will provide some rigidity for the roof when it goes on next week.

The other big item was wiring.  I wish I could say that I had a carefully drawn schematic with everything perfectly labeled and annotated.  But I don't yet - it's basically a napkin sketch and even there I made some flying changes that haven't quite gotten committed to paper - yet.  In fact those lovely yellow wires - I'm sure they will be for something, but at this point I've no idea what.  They will terminate to the 3rd switch at each door and home-run back to the load center for some purpose to be determined at a later date.  

This is a great time to talk about my new favorite thing to come out of this project.  I thought it was the Kreg pocket hole system, but I was wrong...
It's Wago connectors!!! The irony is that in another lifetime I used to sell thousands of Wago terminal blocks, but had never stumbled across these gems - the ultimate replacement for wire nuts and butt splices.  The connectors have a lever that you open, slide in the wire to the stop, and close the lever.  It's that simple.  No guessing about whether you have a solid crimp, and definitely no question about whether the wire nut bit all three wires.  

The connectors probably saved me an hour or more on the wiring, especially since they can be opened and closed multiple times, which is very handy when you are trying to keep wires sorted into runs, and they do get entangled.

    absolutely amazing!!!

What's that over head? Roof, Roof? No...

 It's the ceiling you stupid dog...

Alright, I know - it's one of the worst dad jokes, but that's where we are today.  The ceiling is in, and I'm working on things like wiring, blocking, and poking holes in the side of the trailer (truly an essay in courage, or my lack thereof).

First-up, I added all the blocking on the sides. I made use of the leftover bits of 3/4" ACX to CNC arcs of plywood that matched the arc of the wall.  Hey, once in a while even the blind squirrel gets the nut!  

A couple of pocket holes, a couple of screws, and a little sculpting with the jigsaw, and they were in.  I had intentionally left them a little proud, and once installed, I cleaned them down to the wall line with a pattern bit.

Next up, wiring for all the lights, MaxxFan, and I'm still not sure what else.  Some sort of little command center up front, but I still don't know quite what - so I'll run a bit of flex conduit and a messenger line in it - just in case I figure it out.  With the exception of the 3-way switches for the cabin lights, I'm home running most all of the lights, and using Wago connectors anywhere I have to join two wires.  No wire nuts or crimps to fail.

I'm not particularly proud of these, nor the reason they exist...  In my jumbled planning, I neglected to consider letting in wireways during the build.  As a result, I had to find a way to get wire down to the light switches in the cabin, and surface molding was not a consideration!

So I chose to make a template and hog out a wireway and switch box.  I CNC'd the templates out of MDF (a really bad idea, BTW).  It's really easy to cut MDF, and if you touch it with a router it will make a 1/4" dip.  Since hogging the wireways took a couple of passes, I had a couple of extra opportunities to inflict non-straight lines as I went along.   I also made a second template to cut in a cover plate on the outside so no weak spot in the aluminum right next to the door.

My porch lights are corner mounted, with  a pigtail.  I used a 1 1/2" Forstner bit to cut a pocket in the wall (a little less than 3/4" deep, and then came down from the top with my trusty Kreg pocket bit (it's just about 5 1/4") to provide a dropper.

Same bit chucked up from the inside of the roof, I cut another hole into that top down hole to get the wire to feed thru.

Obviously a little out of sequence, but it looks pretty good up there.

Finally, to fill in the wireways that I hogged out, I 3D printed a set of covers that snuggle in pretty well around the bundle of wires going down the wall.  Printed in 6" sections, and trimmed as necessary.

Yet another excuse to pull out the printer and tell my wife how much I 'saved' by printing my parts!

Wireway covers deployed (well - sort of).  I'll need to move them, trim to fit, and add a little dab of glue, but you get the idea.

Next up - more wiring, wiring the electrical panel, insulating the ceiling and installing the *roof*, and then starting on the dreaded galley hatch and lower front.  

Fairly square!!!

 

I've been looking forward to this day with more than a little fear and trepidation, and a bit of giddy excitement too.  It _should_ have worked.  Everything was cut by CNC - it really should be identical.  The base is square.  The walls lined up on the ground.  It should have fit...

And it did!  It's glued, screwed and plumbed, the top and bottom are within 1/16th of an inch, the front-back is pretty much dead square, and it's ready for the ceiling and spars.  

Update - interior work

If there is one area that I badly underestimated, it's the amount of time that is required to finish the interior.  Varnishing 40 square feet of space is a lot.  Getting it smooth and doing 3 or 4 coats is a whole lot.  And then there's the time spent figuring out that you really didn't think you A/C initial plan through very well, and you will need to do something else.  

I'll do a separate post on the A/C system, but in the short - the return duct will be a 12¨ panel in the headboard, and the cold air will come out of a duct that runs up the middle of the front wall from the top of the headboard.  Not the first change order to hit this project, and I'm sure it won't be the last 

Reddit fans are fond of 'today I learned..." factoids.  Well today I learned that cabinet doors are typically 3/4¨ thick.  So in order to make my Euro hidden hinges work for the headboard, I have to pad the top 3" of the backside of the doors with an extra layer of plywood.  

I'm learning to be a master of multi-tasking.  I generally have 3-4 'tasks' in flight at any given time in the shop, and bounce between them - let the glue dry on 'a', sander is available so work on 'b', finish room is open, so prep 'c' and get it in the finish room, back to 'b' to glue it while 'c' dries.  Grab 30 minutes on CNC when that opens up.  That's pretty much every trip to the shop.  Oh, and the occasional side trip to Menards for brads or whatever.

One other lesson.  While Festool sandpaper is the absolute bomb, I've found that "Serious Grit'' (Amazon) wears almost as well, cuts almost as well, and costs about 50% what Festool paper does.  

This coming weeekend will be devoted to varnish, and maybe, just maybe install all the cross-trailer panels and get the left side stood up!  (more likely early next week, given how much time it takes to varnish...)

One other side note - I *think* all the electrical is in - transfer switch, solar charging, battery system, fuse box, etc.  Now I need to think about lights and switch panels.  Dang this stuff sneaks up on you...

Milestone #4 - first wall up!

If I count completing the frame as #1, the floor as #2, and getting the walls assembled as #3, getting the first wall stood up is an easy #4.  This afternoon my neighbors came over and helped me stand up the first wall.  

Taping off the work area and buttering the seam with PL.  I used Loctite PL Premium.  I really don't enjoy working with PL - sort of like spreading peanut butter - a peanut butter that will rebound away from the surface if you spread it too thin or too fast.  But I have used it enough that I trust it, and *know* it will provide a good bond.

Stood up, clamped to the really big triangle, which is clamped to the trailer frame on the left, and the top of the door opening.  Plumb checked to make sure we're within about .1 degree of vertical.  

Pocket screws every six inches into the floor (great invention!) and screws on the outside every 4-6 inches to secure the outer walls.

From the outside.  and the fenders showed up while we were installing the wall!

From the front.  The big triangle is a 2x8x10' simply cut in half, and the triangles are one of the door cut-outs.  And then pocket screwed together.  I cut the 2x8 with the sliding miter saw at the shop, and then ran the 5' sections thru the planer just to flatten and smooth out a bit. 

It's heavy enough to stand on its own, but I clamped it to the trailer frame on the far side to keep it square.

Weekend Update

 This was supposed to be a post about the first wall was standing and here's the video.  Didn't quite get there for a number of reasons, but I did:

• 
  Get the right side wall (left has been ready for a week) pocket drilled, grooves cleaned out, and a couple of little annoyances fixed.  Rounded corners cleaned up too!
• Varnished back wall, ceiling panels
• Accumulated a little more hardware in prep for final assembly. 

Fridge and stove shelves going together.  It took a little more time and a couple of false starts to get the clearance right so that things fit together properly.  

Hint: 40 thousandths seems about right.  Teeth are 1.98 and notches are 2.02 inches.  

Glued together with Titebond II.  They seem to be plenty strong.  

I got this task out of the way mostly on timing, and to ensure I could size the back partitions correctly. 

Roof spars bundled up to cut wireways.  Yes, I certainly could've done it on the table saw with a sled and a dado blade, but it would take me longer to set that up than it took to draw it in CAD and cut it with CNC.

These started out as an 11' plank of basswood that was pretty straight, dry and pretty good grain structure.  A few passes on the table saw and we have 1 1/4x 2¨ spars.  And I still have a nice bit of basswood in reserve (probably for the hatch!)

The sides came home.   You can see the cladding aluminum standing behind them waiting its turn.  The right side (shown here) will probably get bolted to the floor on Wednesday.

   

Last but not least, the trailer chassis finally got out of the garage, and the floor got checked for fit.  I always assumed it would fit properly - and it did.  

Mistakes were made...

 

The nice thing about CNC is that you can pre-plan you dimensions, create 3D images of the various pieces, model them in place, and *know¨ that what you have drawn will most likely probably fit together flawlessly... 

Until you do something like change the model of cooler you have designed for, andddd... the cooler you bought is 2 inches taller than the one you drew the plan around, and... there was just enough clearance build in for the old one. So a quick trip thru the CNC to make a 3/4¨ slot template, a trip to Rockler for a top bearing 1/2¨ router pattern bit, a little dark stained cherry, and Bob's yer uncle.  One of my shop buddies is fond of saying '' no such thing as a mistake, just an opportunity for an accent feature''  So there's now an ¨accent strip¨ under the counter in back!

Pocket screws

 Kregs pocket screw jigs are one of those next level tools.  I've done a couple of pocket screws the old way - angling a drill to try and get it to approximate a toe nail, having it split out the board, go in too deep, too shallow, too... whatever.  

But with a simple jig set, perfectly sized drill bit, and screws designed for the task - wow.  Just stupid simple.  And this is another task that could be done while the panel was sitting on a table - much easier than trying to do it 'in situ'.  

Walls 'done'!

 Well, ok.  Not 'done-done', but nearly done.  The final coat of epoxy is hardening on the bottom right now, and I'm taking the afternoon mostly off to go ride my bike.  

Things I learned from these - 

Baltic birch soaks up Titebond 3 (varnish too!) like a sponge.  It takes a lot more glue than I expected, so I'm glad I bought a gallon!

When planning to cut the top layer rabbet using the core layer as a guide, make sure the core rabbet is deep enough for your router bit stack height (I had to grind off most of the screw holding the bearing in place to get it to fit.)

The use of some staples is almost unavoidable.

Don't forget to plan and clean a pocket for your door side switches, and the cable next to them.  (I did on the first wall - will go in from the back, mill out a path, and then cover it.  Oops - lotta extra work!